Replaced os.path.join with urljoin in rawclient.py

[GrandMoff100]

Closes #98

[GrandMoff100]

MegaLinter status: ✅ SUCCESS

Descriptor	Linter	Files	Fixed	Errors	Elapsed time
✅ ACTION	actionlint	4		0	0.06s
✅ CREDENTIALS	secretlint	yes		no	0.91s
✅ GIT	git_diff	yes		no	0.01s
✅ JSON	eslint-plugin-jsonc	2	0	0	1.01s
✅ JSON	jsonlint	2		0	0.58s
✅ JSON	prettier	2	0	0	0.6s
✅ JSON	v8r	2		0	2.16s
✅ MARKDOWN	markdownlint	6	0	0	0.36s
✅ MARKDOWN	markdown-link-check	6		0	2.56s
✅ MARKDOWN	markdown-table-formatter	6	0	0	0.29s
✅ SPELL	misspell	26	0	0	0.07s
✅ YAML	prettier	7	0	0	0.76s
✅ YAML	v8r	7		0	6.54s
✅ YAML	yamllint	7		0	0.22s

See errors details in artifact MegaLinter reports on CI Job page